Influence of dietary Vitamin E level on egg production of broiler breeders, and on the growth and immune response of progeny in comparison with the progeny from eggs injected with Vitamin E

Broiler breeders were allocated at random to one of four experimental diets containing graded levels of supplementary Vitamin E (25, 50, 75 and 100 mg kg−1) between 24–54 weeks. At 40 weeks of age, eggs from breeder hens receiving 25 mg kg−1 diet were subjected to in ovo injection of Vitamin E at a level of 0, 2.5 and 5.0 mg per egg. Hen housed egg production, egg weight, hatchability, neonatal chick weight and performance of offspring broilers were not influenced by the levels of Vitamin E in the breeder diets. The Vitamin E content in the eggs was significantly (P≤0.001) increased by the increasing supplements of Vitamin E up to 75 mg kg−1. The chicks hatched from the eggs of the breeders receiving dietary supplement of Vitamin E or from the eggs injected with Vitamin E at a level of 2.5 or 5.0 mg per egg were used to determine growth and immune response to 21 days in battery brooders and growth performance to 42 days in floor pens. No significant difference in growth performance at 21 days were observed due to the dietary Vitamin E supplements or Vitamin E injection in the eggs. The antibody titers to killed Newcastle disease vaccine were significantly (P≤0.05) increased by the level of Vitamin E supplements in the diets or direct injection into eggs and, in ovo administration was more efficient in increasing the immune response. Higher final body weight at 42 days, feed conversion efficiency and reduced mortality (P≤0.05) were observed with the broilers hatched from eggs injected with Vitamin E.